Philosophy of science

The philosophy of science is the branch of philosophy that examines the foundations, methods, implications, and normative structure of scientific inquiry. It is not a meta-discipline standing above science, judgmentally assessing its validity from the outside. It is a reflexive practice — science turning its own methods upon itself, asking what it means to know, to explain, to confirm, and to be wrong.

The field occupies the boundary between epistemology and the history of scientific practice. Its questions are not abstract: What counts as evidence? When does a theory fail? How do communities decide what is true? These are operational questions for working scientists, and the philosophy of science provides the conceptual scaffolding that makes them explicit.

Demarcation and the Boundary Problem

The most famous question in the philosophy of science is also the most misunderstood: what distinguishes science from non-science? Karl Popper's answer — falsifiability — is elegant but incomplete. A theory that makes no falsifiable predictions is not thereby worthless; it may be heuristic, programmatic, or interpretive. Popper's criterion works well for physics, less well for systems biology, and hardly at all for the historical sciences, where the events under study are unrepeatable and the predictions are retrodictive.

The deeper problem is that the demarcation problem assumes there is a single scientific method, universal across domains. There is not. The methods of molecular biology, cosmology, climate science, and machine learning are as different from each other as they are from non-scientific practices. What unifies them is not a method but a social norm: the commitment to publicly contestable evidence and the willingness to revise belief when the evidence demands it. The boundary of science is not logical; it is sociological.

Theory Change and the Structure of Scientific Revolutions

Thomas Kuhn's 1962 work The Structure of Scientific Revolutions transformed the philosophy of science by treating scientific change as a historical process rather than a logical one. Kuhn argued that science proceeds not by steady accumulation but by alternating periods of normal